I'm trying to compare/contrast the surface gravity of Sonic's Möbius with that of Marioworld. There's an excellent article  that analyzed Marioworld's surface gravity across several games, wherein the mean average turned out to be 7.51(-) g. In trying to find similar material on Möbius, I've so far found only some material for generic differences between the games  and Source engine gravity  (after which I broadened my search to Sega Genesis's gravity in general, but no luck so far); Googling quite a few terms has been singularly unforthcoming.
I'm not asking in order to write code for game development. I'm curious about it for a much more mundane reason: I'm writing a fanfic in which Sonic noticed the difference immediately upon arrival. This means that I don't require 5 SD of accuracy (my OCD would love that, of course), but would like more than my own ballpark guesswork.
 What are the different versions of Sonic the Hedgehog (1991) and what differs between them?
 What is the gravity model in Source engine games?